Solve for r and t: 6r - 3t = 6 6r + 8t = -16
1 answer:
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Answer:
B
Step-by-step explanation:
This is a distance-rate-time problem, so we need to use the equation: , where d is the distance, r is the rate, and t is the time.
Here, we know that the total distance is 150, so d = 150. Also, we are given that Sergio's rate is 60 mph, so r = 60. Put these in:
d = rt
150 = 60t
To solve for t, we divide both sides by 60. Because we are dividing and not multiplying, we know that B is the only one that is incorrect.
Hope this helps!
Answer:
The 90% confidence interval for the mean test score is between 77.29 and 85.71.
Step-by-step explanation:
We have the standard deviation for the sample, so we use the t-distribution to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 25 - 1 = 24
90% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 24 degrees of freedom(y-axis) and a confidence level of . So we have T = 2.064
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 81.5 - 4.21 = 77.29
The upper end of the interval is the sample mean added to M. So it is 81.5 + 4.21 = 85.71.
The 90% confidence interval for the mean test score is between 77.29 and 85.71.